We start by fixing this in the already-present OSC_Config class so OSC
can move forward. This change needs to get ported down into
os-client-config in the near future, maybe even soon enough to make the
client library freeze this week.
* Add the pw-func argument to the OSC_Config (or OpenStackConfig) __init__()
* When looping through the auth options from the KSA plugin look for any
that have a prompt defined and do not have a value already, so ask for one.
Closes-bug: #1617384
Change-Id: Ic86d56b8a6844516292fb74513712b486fec4442